Seth Godin has a great post about philanthropy and the sacrifice that is involved. From Seth:
Peter Singer is famous for posing a stunningly difficult question, paraphrased as, "If you are walking by a pond and you see a child drowning, do you save her? What if it means ruining a very fancy pair of Italian shoes?" Okay, if we assume the answer is yes, then why not spend the cost of those shoes to save 20 kids who are starving to death across town or the world? There's really no difference. Or by, extension, invest in research or development that solves a problem forever... The issues are proximity and attention.

My take is that most people would instantly save the kid, but given the choice, probably wouldn't take the road by the pond again any time soon. We like to avoid these situations, because these situations make us uncomfortable.

Avert your eyes.

The reporter tells you, I'm going to show you a video of the meat you're going to eat for dinner being slaughtered. Avert your eyes. Or the fundraiser says I'm going to tell you about easily avoidable suffering in the developing world. Avert your eyes...

It boils down to a simple question, "how much is enough?" She knows that one iPod is all she needs, but she wonders how much philanthropy is enough? And this is a key marketing question for anyone seeking donors.

Do I have to use up all my Italian shoes? How much is my share? ...and at some point, will we end up avoiding Singer's question altogether?

If you don't give anything to good causes, then you define enough as zero and you have no worries about achieving 'enough'. A sad but effective strategy.

If you give money to emergencies, friends with the guts to ask and the occasional feel good moment, you've also defined 'enough' in an easily achievable way. Your gift is a reaction to inputs.

What about people who make substantial, anonymous donations to long-term causes? How do they know what's enough? How do they decide that now it's okay to go out for a fancy dinner and not send the money to the worthy cause instead? If the solution isn't clear, if it's limitless, how do they avoid the temptation of avoiding the problem by doing nothing?

Marketers at good causes have a real challenge as they try to raise money from people who aren't billionaires. As they approach people with $10,000 or $100,000 in the bank, this fear of not seeing a limit is very real, and if it's not confronted, they will fail at both raising the money and generating satisfaction for the donor.

The Mormon Church says, "tithe". Loosely paraphrased, they say, "10% is a lot, and 10% is enough." This is actually very smart, because they've created a difficult but achievable standard, a way to be a member of good standing in their tribe.